The term Jnana has been originated from Jna Dhatu of Samskrit which means to know. The knowledge may be true or false, in which the true knowledge is known as Prama while false knowledge is known as Aprama such as knowledge of rope in the snake. In any knowledge the knower is known as pramata, the knowing object is known as prameya while the means of knowledge is known as pramana. In Indian Philosophy six pramanas have been accepted - Pratyksha or Perception, Anumana or Inference, Sabda or word, Upamana or Comparison, Arthapatti or Postulation and Anupalabdhi or non cognition. Different schools have accepted the different number of Pramana.

As far as pratyaksha pramana is concerned, then this is known as prime pramana. Sometimes in order to put it at the level of prama it has been said that there is no need of proofs to perception. Etymologically the term Pratyaksha is made up of two words - prati + aksha, which mean in front the eyes, in general the knowledge received by all sense organs, is known as pratyaksha.

In order to clarify Pratyaksha, Maharshi Gautama said that- The knowledge originated by the contact of sense organs with the objects is perception if it is Avyapdeshya, Avyabhicari and Vyavasayatmak, where - Avyapdeshya means Nirvikalpak pratyaksha, where no knowledge of name and character does happen.Vyavasatmaka means Savikalpaka pratyaksha, where knowledge of name and character happens. Avyabhicari, which indicates towards doubtless knowledge.

Similarly Acarya Gangesh upadhyaya the founder of Navya Nyaya while giving his definition said that the knowledge originated by the contact of sense organs with object is knownn as pratyksha. Here in sense organs the internal sense organ mind is also included other than five external senses. In Nyaya six types of contacts between senses and object have been accepted as:—

  • Samyog- such as knowledge of pitcher.
  • Samyukta samvaya- knowledge of colour of pitcher.
  • Samyukta samvet samvaya- knowledge of colourness of pitcher.
  • Samvaya- knowledge of word.
  • Samveta samvaya- knowledge of wordiness.
  • Visheshan visheshyabhava or Perception of absence- knowledge of absence of pitcher.

As far as classification of Perception in Nyaya philosophy is concerned, then First of all perception in classified in two parts- Nitya and Anitya, in which Nitya pratyaksha is related to god, while the Perception of human beings is known as Anitya pratyaksha. There are two types of Anitya pratyaksha - Nirvikalpaka and Savikalpaka.

In Nirvikalpak Pratyaksha there is no knowledge of name and character. This is a kind of unclear knowledge, Such as it is a person or stem; while in Savikalpak Pratyaksha we have the knowledge of name and character. It is a clear knowledge, such as identification of the person. This Savikalpak pratyaksha is also of two types-Laukika and Alaukika.

In Laukik pratyaksha there is direct contact of sense and object. There may be two types of Laukik pratyaksha - Bhaya or External and Manas or Internal. In first one Knowledge received by five sense organs have been included, such as the knowledge of word, touch, colour, taste and smell through ear, skin, eye, tounge and nose respectively; while in second one the Perception by mind has been included. In order to clraify the Alaukik Pratyaksha in Nyaya Philosophy it has been mentioned that here we have no direct contact sense with objects. There are three types of Alaukik pratyaksha - Samanya Lakshna, Jnana Lakshna and Yogaja.

In order to clarify the first one it has been said that when by the perception of particular object we do the perception of universal, such as the knowledge of cowness on the basis of perception of cow. In Jnana Lakshana Pratyaksha one sense organ starts doing the function of other, such as the knowledge of softness of the grass after the perception of its green colour. Here after the contact with eyes only the judgment in based on skin. In Yogaja Pratyaksha there is no baudation of space and time. In Indian philosophical tradition so many such Yogies have been accepted who have done this divine perception. The persons do these kinds of perceptions are known as Yukta.

In addition to Nyaya philosophy other Indian philosophy schools, the perception have been dicussed and they have also acepted the Nirvikalpaka and Savikalpaka Pratyaksha in some way or other.

As far as Anumana is concerned then the knowledge of unknown on the basis of known is named as Anumiti Prama and the mean of Anumiti Prama is Anumana which is made of two worlds - Anu + Mana, which means letter knowledge. But the question is often which Anumana in possible? It answer in Anumana is possible after the perception.

In general words in order to define Anumana we can say that it is such a rational process in which on the basis of knowledge of a object the certain knowledge of other object is received, in which the object known before is named as Hetu, while the later known object is known as Sadhya. There are three steps in the process of inference:—

  • Sadhya in that, which has to be proved.
  • Paksha is that, where we has to prove the sadhya.
  • Hetu is that, on which perception, we prove the Sadhya, becouse there is relation of Vyapti between Hetu and Sadhya. For example -
  • All the places of smoke are the place of fire.
  • The mountain has smoke.
  • Therefore the mountain has fire.

In the above example - Sadhya is fire, Paksha is mountain and Hetu is smoke.

As far as clarification of Anumana is Nyaya philosophy is concern, then it has been done in several ways- such as according to traditional Nyaya philosophy, on teleological basis and on the basis of Navya Nyaya. According to traditional Nyaya (Gautam) there are three types of Anumana -- Purvavata Anumana is that, which on the basis of known cause we come to known about unknown effect, e.g. - Inference of rain on the basis of cloud. Sheshavata Anumana, in Which on the basis of known effect, we do the inference of unknown cause. e.g. - on the bsis of malaria, the inference of Anopheles mosquito. Samanyatodrishta Anumana- in which there is no relation of cause of and effect but even then the inference is possible, such as one can infer about the swiming ability of animal on the basis of its four legs.

Similarly teleologically Anumana is classified is two parts Swarthanumana and Prarthanumana.Where the first one is subjective and this is a psychological process. In which there is no need of statements or components while the process of Pranthanumana has been to make it clear to some other, that's why it needs statements of components. In Nyaya philosophy five statements have been accepted as Pratigya, Hetu, Udhaharana, Upanaya and Nigmana. For example -

  1. There is fire on the mountain.
  2. Because this mountain has smoke.
  3. All places of smoke are places of fire. e.g. kitchen.
  4. This Mountain is also has smoke.
  5. Therefore this mountain has fire.

As per as, Anumana in Navya-Nyaya is concerned, then three forms of Anumana has accepted.

  1. Kevalanvai - In which, the vyapati statement or udhahrama is positive, e.g.
    • This servant is employable.
    • Because he is honest.
    • All the honest servant are workable.
    • This servant is honest.
    • Therefore this servant is also employable.
  2. Kevalavyatireci - Where vyapti statement in negative such as. E.g.
    • This is Himalaya.
    • Because this is highest Mountain.
    • Which is not highest is not Himalaya.
    • This Mountain in highest.
    • Therefore this is the Himalaya.
  3. Anvayavyatireci - Where vyapati statement can be both positve and negative. such as on the basis of smoke, the knowledge of fire. The example of positive vyapti statement is -
  • All the places of smoke are places of fire.
  • The Mountain has smoke.
  • Therefore Mountain has fire.
While the example of negative vyapati statement is
  • All the fireless places are smokeless.
  • This mountain has smoke.
  • Therefore this mountain has fire.

Although, anumana is possible on the basis of pratyaksha, but the importance of anumana is that if we reject the it, then all the practical behaviour of human beings will be stopped because human beings done all action on the basis of the inference that he will achieve his objectives. In addition, the rationality of human beings is also proved on the basis of his ability of inference.

As far as Hetvabhasa is concerned then in the parathanumana of Nyaya philosophy, five statements have been accepted as Pratigya, Hetu, Udaharana, Upanaya and Nigamana; in which, the 'Hetu' has specific importance because if Hetu is not proper, then the process of anumana will be deteriorated. That is why in order to clarify the 'Hetvabhasa', it has been mentioned in Nyaya that this is a false inference, which occurs due to the fault of Hetu. The scholars of Nyaya philosophy believes that, there are certain parameters for Hetu -

  1. Pakshadharmata which means presence of Hetu in Paksha. Such as presence of smoke in the mountain.
  2. Sapakshasatva which means presence of Hetu in sapaksha. Such as presence of smokein kitchen etc.
  3. Vipakshasatva which means absence of Hetu in vipaksha. Such as absence of smoke in river etc.
  4. Asat Pratipakshatva which means to prove the contrary object to sadhya, there shall be absence of necessary Hetu. Such as absence of necessary Hetu to prove water on the mountain.
  5. Abhadhitatva which means the Hetu shall not be broken by later perception.

According to scholars of Nyaya philosophy, in case of lacking of any one of them the Hetu will deteriorate and the inference based on it will be definitely wrong. This is known as Hetvabhasa, which is supposed as of five types:—

  1. Savyabhicara - When the Hetu is available is sadhya but also exits with other objects, then it is known as savyabhichara Hetvabhasa. It may be of three types -
    1. Sadharana savyabhicara hetvabhasa occurs when Hetu is available in vipaksha as well as sadhya e.g. Ram is Brahaman, because he wears sacred thread. Here, the Hetu, (Sacred thread) in available in sadhya (brahaman) but it is also available in krhatriya and vaishya. Here the parameter of vipakshasatva is over ruled.
    2. Asadharana savyabhicari Hetvabhasa occurs when the Hetu is not available anywhere except paksha e.g. The word is eternal because it is heard. Here, the Hetu (the heard) is found only in paksha (word) not any where else. Here the parameter of sapakshasatva is over ruled.
    3. Anupsanhari savyabhicari Hetvabhasa occurs when no object other than paksha does remain to see the co-existence of Hetu and Sadhya e.g. All the objects are perishable because they are known. Here apart from 'all object' nothing remains where we can see the perishability and knowing tendency. Therefore here parameter of both sapakshastva and vipakshastva have been over ruled.
  2. Viruddha Hetvabhasa occurs when, hetu instead of proving the sadhya, proves just contrary to it. e.g. The air has weight because it has emptiness. Here the hetu (emptiness) proves the lightness instead of weight.
  3. Satpratipaksha Hetvabhasa occurs when two strong hetus present simultaneously, in which one proves the sadhya, while other one disproves the sadhya. e.g.Word is eternal because it is heard. Word is not eternal because it is an event. Here in the first example Hetu (heard) is proving the eternity of the word, while in the second example Hetu (event) is proving the non-permanency of word.
  4. Assidha Hetvabhasa occurs when the hetru is false itself. It also has three types -
    1. Ashrayasiddha Hetvabhasa occurs when the shelter of hetu (means paksha) is asiddha itself. e.g. Golden mountain has fire because it has smoke. Here there in no existence of golden mountain so there is no question of existence of smoke.
    2. Swarupasiddha Hetvabhasa occurs when the nature of paksha is not coherent for keeping hetu in it.e.g. The river has fire because it has smoke. Here the nature of river not coherent to keep the smoke in it.
    3. Anayathasiddha HetvabhasA occurs when the relayion of vyapti depends upon some conditionality e.g. there is smoke on the mountain because it has fire. Here the rekation of vyapti between hetu (fire) and the sadhya (smoke) is depending upon the condition that the fuel is wet.
  5. Badhit Hetvabhasa occurs when the anumana violated by future experience e.g.The ice sinks in the water because it is solid. But by later experience we can see ice of floats in the water.

Altogether we can say that in savyabhichar hetvabhasa hetu cann't prove sadhya, in viruddha hetvabhasa, hetu proves just contrary to sadhya, in satpratipaksha hetvabhasa two strong hetu counter balance each other, in asiddha hetvabhasa the hetu dis proves it self, while in badhit hetvabhasa the hetu broken by future knowledge.

As far as Vyapti is concerned, then it is a kind of relation available two objects in which are in known as vyapya and other one vyapaka. In which something is distributed in known as vyapya, while which one is distributed is known as vyapaka. Such as in example of fire and smoke, the smoke is vyapya and fire is vyapaka, because the smoke has fire. They are known as hetu and sadhya in the process of inference.

Altogether, the relation of vyapti is the basis of inference, because only on this basis after the perception of hetu we do the perception of sadhya. There may be two types of vyapti - Samavyapti which moves in both directions e.g. the human beings and rationality.Vishamvyapti which moves in a certain direction e.g. smoke and fire.

In Indian philosophy Carvaka did not accept the relation of vyapti and that is why they did not accept the anumana as pramana, while in cretarary all other Indian philosophy schools have accepted the relation of vyapti and have also discussed over necessary characters of it - Niyat sahcarya (Permanent coexistence) means to live together permanently. Avyavicarita means there shall be no exception. Ekantikta (dependency on one) means dependency on one and only. Avinabhava means there shall be no existence in case of absence. Anaupadhikta (unconditionally) means there shall be no conditionality. Because if we accept condition, then we can prove the relation of vyapati between fire and smoke and the condition will be wetness of the fuel.

In Indian philosophy, the theory of vyapati in Buddhist and Nyaya philosophy is important but here also in Nyaya philosophy the theory of Buddhist is refuted and for vyapati few decisive parameter have been mentioned. Anvaya (Agreement) what ever the places of hetu are the places of sadhya.Vyatireka (Disagreement) wherever the sadhya is absent, absence of hetu as well. (Vayabhicargrah) means, there shall be no exception. (Upadhinirasa) means there shall be no condition. (Tarka) means logic, because if we reject the relation of vyapti between smoke and fire, then the statement "all the places of smoke are the places of fire" will be false and in this conditon its just contrary statement "Some places are smoke are not the places of fire" must be true. But we have no example regarding this, therefore the statement "some places of smoke are not the places of fire" will be false. In this condition the statement just contrary to it must be true that is "All the places of smoke are the places of fire". This is the vyapti.

In addition to all, according to scholars of Nyaya the rejection of vyapati is the rejection of cause and effect. If we reject the causation then the question will be, what is the need of fire, to cook and water to satisfy our thirst. So we can reject the cause and effect, therefore we can't reject the vyapti as well, because the Hetu and sadhya in the relation of vyapti are cause and effect respectively.

As far as Shabda is concerned, then knowledge received by sabda in known as verbal testimony and the means of it shabda pramana. All kinds of words can not be supposed to be authentic, but only those words can be accepted which originated from authentic sources. The words may be vocal or verbal. Verbal words may be meaningful or meaningless. Here only meaninful words are pramana which is originated from an authentic source. Similarly the word may be visible and invisible. Similarly the words may be vedic and practical. The power of expressing the meaning in the word is known as 'Sanketa', some of them are given by god, while some are given by human beings. They are known as Ajanika (conventional) sanketa and Adhunik (modern) sanketa. In addition according to Nyaya there are four parameters for meaningful of a statement -

  1. Akansha (Expectation) - The statement can't supposed to be meaningful without fulfilling the expectation of the words.
  2. Yogyata (Ability) - The words used in a statement must have the capability to perform the action mentioned.
  3. Sannidhi (Closeness) - There must have spatial and temporal closeness.
  4. Tatparya (Sense) - The meaningfulness of the statement can't be defined without keeping the intention of speaker.


In Indian philosophy except Carvaka, Buddhism and Vaishesika all other schools have accepted sabda as independent pramana.

As far as Upamana is concerned, then the knowledge on the basis of similarity or resemblance is known as upamiti prama and its mean is known as upamana pramana. It is made of two words upa + mana. Upa means similarity and Mana means knowledge. Such as the knowledge of wolf on the basis of dog. But the later Nyaya scholars have also accepted the difference in add to the similarity as the base of upamana. They accepted three kinds of upamana - Sadharmyopamana which based upon similarity or resemblance e.g. the knowledge of Nilgaya and the basis of cow. Vaidharnyopamana which is based on dissimilarity e.g. the knowledge of elephant on the basis of buffalo. Dharmamatropamana which is done on the basis of specific individuality e.g. the knoweldge of camel as the ship of desert.

In Indian philosophy only Nyaya, Mimamsa and Vedanta have accepted upamana as an independent pramana, while Carvaka refuted it and other schools have merged it with other pramana. Although Nyaya and Mimamsa accepted it but where Nyaya discussed about upamana on the basis of object heared then the Mimamsa accepted upamana on the basis of objects perceived.

As far as Arthapatti is concerned, then if a phenamenon can't be clarified unless we don't accept the truthness of other incident, then the pramana by which we came to known about the truthness of other phenomena is known as Arthapatti, e.g. the big unit Devdatta doesn't take meal in the day. This can't be understood unless we don't accept that he takes heavy diet in the night. The means of this knowledge is arthapatti ,which may be of two types:— Shrutarthapatti occurs when, in order to prove the truthness of the phenomena heard, it is necessary to accept the truthness of other phenomenon. example of Devadatta. Drishtarthaptti occurs when the phenomena preceived can't be understood unless we accept the truthness of other phenomenon.Such as Snake and Snake Charmer. In Indian philosophy arthapatti has been accepted as an independent pramana only by Miamasa and Advaita Vedantis, while in other schools it is merged with Anumana pramana.

As far as Anupalabdhi is concerned, then the perception of non-existence is happened by which pramana that is known as anupalabdhi, such as there is no pitcher in the room. Here the perception of non-existence of pitcher have been done. The anupalabdhi has been accepted as an independent pramana only by Kumaril Mimamsa and Vedantis, while other schools have merged it with perception. The schools which have accepted the anupalabdhi as an independent pramana said that it can't be merged in any other pramana because where other pramanas are perceived the positivity while anupalabdhi is one and only pramana which perceives the non-existence.

In Indian philosophy we can see three classes regarding 'Abhava' and 'Anupalabdhi'. Firstly schools which accepted the abhava as an independent Padartha but don't accept anuphalabdhi as an independent pramana, such as Nyaya- Vaisheshika. Secondly the schools which accepted the abhava as an independent Padartha and anupalabdhi as an independent pramana, such as Kumaril Mimamsa. Thirdly the schools which neither accepted abhava as an independent Padartha nor anupalabdhi as an independent pramana, such as prabhakara Mimamsa.

As far as theory of causation is concerned, then this is a fundamental concept of philosophy which means, there will be cause of every effect. It is equally important in both Indian and western philosophy. Actually as the Karma theory is important to explanation the moral world; the theory of causation is important to explain the material world. In brief without accepting the theory of causation we can't explain the material world.

As far as Indian philosophy is concerned then the different schools have explained the theory of causation differently. Roughly we can see two types of theories - firstly Satkaryavada, which believes that the effect is already presented in the cause and secondly Asatkaryavada, which believes that he effect is not already presented is the cause, but it is a new creation.

As far as satkaryavada is concerned then it is mainly supported by Samkhya and Vedanta. Ishwar Krishna in his Samkhyakarika presented five arguments in favour of Satkaryavada -

  1. Asadkaranat which means reality can't be originated from unreality, i.e. if the oil is unreal in the sand particles, then we can't get oil, while the oil in oilseed is real, so it can be easily achieved. It proves that the effect in already presented in its cause.
  2. Upadanagrahanat which means only a specific material cause can produce a certain effect, such as clay for pitcher, which proves that the effect is already presented in the cause.
  3. Sarvasambavabhavat which means, if effect is not already present in the cause them we have to believe that any effect can be produced from any cause; while actually it is not possible.
  4. Saktasyashakyakaranat which means for a specific effect we need an eligible cause, which itself proves that effect is already presented in the cause.
  5. Karanabhavat which means the cause and effects are not two separate existences, while they are the name of two stages only, in which the cause is unexpressive stage, while the state of effect is expressive stage. They are two sides of a same coin, therefore no question of new creation, because the effect is already presented is the cause.

In addition to prove the satkaryavada, another argument has been given that the ratio in which we do change in the cause, we see the change in the effect in same ratio, which proves that the effect is already presented in the cause. Above all in the Tatva kaumudi commentry of Samkhyakarika the cause and effect have been mentioned as the tortoise sometimes hide its organs and sometimes reveals, similarly in the hidden stage the cause hides the effect inside, while in the expressive stage produce it in the form of effect. Therefore we shall not discuss over any new creation here. This is the Satkaryavada, which can also be compaired with Potentiality and Actuality of Aristotle.

In Indian philosophy we can see the two types of satkaryavada:—

  1. Prinamavada
  2. Vivartavada

According to parinamavada the cause actually changes the effect, such as the change of milk into curd. This was supported by Samkhya and Ramanuja. The theory of Samkhya is known as Prakriti parinamavada, while the theory of Ramanuja is known as Brahman parinamavada. While according to Vivertavada the cause does not change into effect actually but only appears to be changed. This was supported in Advaita Vedanta and Mahayana Bauddha. Here the theory of Shamkaracarya is known as Brahmavivartavada, the theory of Shunyavadis as Sunyatavivarartavada while the theory of Vigyanavadis is known as Vigyanavivartavada.

As far as Asatkaryavada in concerned then according to it, the effect is not already presented in the cause, but it is a new creation. That is why, it is known as Arambhavada as well. It is mainly supported by Nyaya -Vaisesika and Hinyani Bauddha. In Nyaya -Vaisesika philosophy in order to disprove the satkaryavada and to prove astkayavada some arguments have been given.

  1. If the effect is already presented in the cause then there is no sense of its production, because it will be reproduction. Therefore the effect is not already presented in the cause.
  2. If the effect is already presented in the cause, then what is the need of efficient cause?
  3. If the effect is already presented is the cause, then why they are marked by different names.
  4. If there is no fundamental difference between cause and effect than why we do not behave with the cause, in the way we behave with effect. Why we don't keep water in the clay and why we need a pitcher for it? Reason behind is the pitcher is not already presented in the clay, but it is a new creation. This is the asatkaryavada.

There are two types of asatkayavada firstly Anityaparmanukaranavada which is the theory of Hinayana and in which the whole creation is explained through temporary atoms; secondly Nityaparamanukaranavada which is the theory of Nyaya -Vaisesika school in which the whole creation in explained through permanent atoms.

Altogether we can say that about the causation, both satkaryavada and asat karyavada have given their arguments.

As far as Pramanyavada is concerned, then it is the theory of authenticity of knowledge, in which we examine that the knowledge recived is authentic or not. If the knowledge received is not authentic, then it will be known as Apramanya and if the knowledge received is authentic, then it will be known as Pramanya. But the question is the knowledge of authenticity or inauthenticitiy of the knowledge will be highlighted by the same knowledge itself or we need some other knowledge for it. Because -

  1. If the authenticity of knowledge is highlighted by the knowledge itself is known as Svatahapramanyavada and if some other knowledge is necesary for it then it is known as Paratahpramanyavada.
  2. Similarly if the inauthenticity of the knowledge is highlighted by the knowledge itself then it is known as Svataha Apramanyavada and if some other knowledge is required to prove inauthantacity of the knowledge then it is known as Parataha Apramanyavada.

In Indian philosophy different schools have accepted different theories then regarding this theory of Nyaya is known as Paratahapramanyavada, because according to Nyaya for both authenticity and inauthenticity of knowledge we need separate knowledge, which have been explained on the basis of success in effort, means if the effort done is successful, then the knowledge is authentic and in case of failure the knowledge is not authentic. Regarding this the theory of Samkhya is known as Svatahapramanyavada, in which for the knowledge of authenticity and inauthenticity of knowledge there is no need of extra knowledge and this is compatible with Satkaryavada of Samkhya.

In this reference according to Mimamsa for the authenticity of the knowledge there is no need of any new knowledge, because the authenticity of knowledge highlights itself, but for the inauthenticity of the knowledge we need another knowledge. Mimamsa thinker Prabhakar is a svatahapramanyavadi because his theory of knowledge is known as Triputipratyakshavada in which all three the knowing object, the knower and the knowledge all three are highlighted. Similarly Mimams scholar Kumaril is also svataha pramanayavadi, whose theory of knowledge is known as Jyantatavada in which he said that the knowledge of knowledge is possible through Gyantata; which is also responsible for the authenticity of knowledge. While in order to clarify Paratahapramanyavada Mimamsa said that we need separate knowledge for it. It means the inauthenticity of knowledge is possible only through any other knowledge and it is named in Mimamsa as knowledge of Sadosh Karana e.g. the clarification of inauthenticity of Knowledge of water in the desert is possible when we come to know this' false cause' the sun rays were reflecting and appearing in the form of water.

But in order to evaluate the theory of pramanyavada of Mimamsa we can say that the theory of svatahapramanyavada can't be accepted, because if the knowledge originates as authentic then how can we explain the illusion. There is no possibility of failure in effort as well.

Regarding pramanya the theory of Buddhism is svatahapramanyavada and parataha apramanyavada, means there is no need of other knowledge for the inauthenticity of the knowledge, while for authenticity of the knowledge we do need separate knowledge but it is also not justified.

As far as Khyativada is concerned, then the term khyati originated from khyan, which etymological meaning is 'Gyana', but in Indian philosophical tradition this word is known as error or illusion. That is why regarding error, whatever theories have been presented in Indian philosophy that is known as Khyativada. Here also different philosophical schools have presented their different theories, in which main theories are:—

  1. Asatkhyativada- This is the theory of Shunyavada, according to which all the subject are metaphysically unreal. Which are neither in the beginning nor in the end, the how they supposed to be in the mid. according to Shunyavada all the substance of the world are neither before the origin nor after the end. In this conditions how they can supposed to be existing in the intermediate time. Since metaphysically all the external object are unreal, that's why the illusion regarding the external object i asatkhyati. This in the asat khyativata of Shunyavada. In orden to oppose it Samkaracarya said that the external objects are not unreal because they have the ability of appearance, while the asat is that which even can't be appear, such as horn of rabit.
  2. Atmkhyativada This in the theory of Vigyanvada, in which the ideas have been accepted as real and external objects are named as totally unreal, but even said that the ideas are appeared as the objects of the external world and this in the illusion. In order to appose this Samkaracarya said that in the absence of external objects no rational being can say that ideas can be appeared as external objects. In addition if external objects are not there, then how can we explain our feelings and accordingly behavior.
  3. Anyathakhyativada and Viparitakhyativada these are the theories of Nyaya and Kumaril respectively and there are numbers of similarities, because both have done the realistic explanation of illusion. According to both, there is a certain subject of illusion. According to both the in illusion contradictory object appears which means appearance of totally a different object. While Samkaracarya said that these theories are not justified.
  4. Akhyativada this is the theory of Prabhakar Mimamsa, who said that there is no concept like illusion, because partial or incomplete knowledge is illusion. Therefore illusion in a mixture of two knowledge as mixture of perception and memory. But according to Samkaracarya the illusion is not mixture of knowledge.
  5. Satkhyativada this is the theory of Ramanuja, because he believed in the reality of the world, thus he accepted satkhyati about illusion, but the question is that is it totally real or partially? Because if it is partially real it can't be named as satkhyati and if it is complete reality then theory of illusion will become false itself.
  6. Sadasatkhyativada theory of later Samkhya and Jaina, according to which illusion is two different knowledge known as one. Because the separate knowledge of snake and rope is real this is the satkhytai, while mixture of both in unreal and this in the astkhyati. Since in Jainism both have been accepted that is why it in known as sadsatkhyativada. But against it Samkaracarya said that real and unreal are contrary like lightness and darkness, so they can't live together.
  7. Anirvacaniyakhyati this is the theory of Samkaracarya according to which at the place of illusion an inexplicable object used to be originated, became the object, originated during illusion can't suppose to be real because it can be broken, can't suppose to be unreal because it has capability of appearance, can't be supposed because both because they are contradictory like lightness and darkness, can't be named as 'not both' because any such object is not possible which in neither real nor unreal. This is the anirvacaniyakhyativada of Samkaracarya. Samkaracarya escaped from any probable objections with the statement that "So for we are affected by Maya we can't answer the related questions and when we get rid of then the questions will not remain, means will be ended itself.